1. Field of the Invention
The present invention relates to an adjustable deflection roll having a roll sleeve supported on a support beam by a plurality of support devices or units. The support devices may include pressure chambers, positioned between a respective support device and the support beam, and each pressure chamber may be coupled to a supply line.
2. Discussion of Background Information
Adjustable deflection rolls similar, in general, to the roll discussed above may also be referred to as bending-adjusting rolls and may be used in roll machines, e.g., calenders or glazing rolls, to exert pressure on a continuous sheet of material, e.g., paper. In use, the adjustable deflection roll and a paper cylinder form a roll gap or nip through which the material sheet is guided. To maintain an application of pressure in as even a manner as possible across a width of the roll gap, i.e., transverse to a feed direction of the material sheet, the support units are designed to adjust pressure conditions along the extent of the roll gap. The support units, which are pressurized by a hydraulic fluid, e.g., hydraulic oil, may be of conventional design in the art.
To distribute the pressure as precisely, and evenly, as possible, it is desirable to control the support devices individually or at least in small groups. For this purpose, a large number of supply lines is required. Of course, as the number of supply lines increases, the width of the rolls correspondingly increases. Further, the supply lines have to be routed through the support beam. However, because there is only limited space available, cross sections of individual supply device should not exceed a certain predetermined value. For example, larger cross sections would adversely effect the support device, e.g., weaken the support device, such that it would be unable to perform its requisite support functio.
While the above-noted drawbacks do not generally lead to problems in control of pressure distribution, problems do arise in the so-called quick release processes of the roll machines. That is, the hydraulic fluid in rolls exhibiting sleeve lift, i.e., the support devices exert an upward pressure on the inside of the roll sleeve or jacket, has to be removed from the pressure chambers as quickly as possible, e.g., to relieve the support units or to quickly lower the roll sleeve. However, quick release processes cannot be satifactorily achieved due to small diameters of the supply lines.